Once you’ve learned how to plant allium bulbs you’ll never look back. Loved by garden designers everywhere (especially at the Chelsea Flower Show) these easy summer bulbs add a bold ornamental look to borders that fits with modern gardens and cottage gardens alike. Whether planted in a drift or bursting up at random, these pretty balls create an eye-catching feature that’s very on trend.
Whether you’ve opted for modern and minimal or natural and free flowing, alliums will add a cool geometric touch to your flowerbed ideas. Positioning them here and there in a drift of ornamental grasses is guaranteed to make an impact, and they also look good popping up in gravel gardens.
Allium blooms look like floaty powder puffs and come in a range of colors, with everything from dark and dramatic purple to pale mauve and all shades of pink, as well as cool white if you prefer a more neutral palette. Whatever your preference there will be something that works.
Buy alliums as bulbs to plant out in autumn, or if you've missed that window then you can also get them in pots from the garden centre and slot them into any gaps in borders for an instant sensation.
Read on to find out more about how to plant allium bulbs in your garden, plus how to care for alliums once they're in the ground.
Are allium bulbs easy to grow?
Allium atropurpureum: the stunning deep red-purple flowers bloom in late spring and early summer
Alliums are one of the best plants for beginners as they are super easy to grow in your garden. Follow these key pointers and help your allium plants to thrive:
- Allium bulbs are easy to grow
- They will flower in late spring/early summer
- Allium bulbs are best planted in well-drained gritty soil
- Thrive in full sun
- Once established, alliums are drought tolerant
- Alliums look good planted with ornamental grasses
- Make great cut flowers for the vase
- Butterflies and bees love alliums
- The sculptural seed heads add autumn and winter interest
When it the best time to plant allium bulbs?
Add colour and structure to summer borders with alliums
Allium bulbs can be bought at the garden center or ordered online for planting in autumn. It's best to plant allium bulbs at the same time as your other spring-flowering bulbs – our guide to planting bulbs has lots of useful tips for this.
Don't worry if you didn't find out how to plant allium bulbs in the autumn, however, as there is an alternative option. You can also pick up potted plants from the garden center or order online for planting in spring and summer. They are widely available. If they're already in flower this also gives you the chance to choose the best flower type for your garden.
Where is the best place to plant allium bulbs?
Tall alliums will benefit from a sheltered spot to protect them from the wind
When finding out how to plant allium bulbs, one of the key considerations is where to plant them. Allium bulbs will generally do best in a sunny spot.
Try planting taller varieties towards the back of a border and shorter-growing alliums in the front. In general, however, alliums are better suited to the middle of a border where the faded foliage will go unnoticed while the flowers put on a show.
For a dramatic display, grow alliums in large drifts through the border, even better if they’re mixed in with grasses. Head over to our guide on how to grow ornamental grasses for our expert tips.
Tall varieties of alliums will do best in a sheltered spot to protect them from the wind.
How to plant allium bulbs
Pollenating insects like butterflies and bees love alliums
- Grow alliums in moist but well-drained soil in full sun. You might want to opt for a sheltered spot if you’ve chosen tall varieties which could otherwise get blown about in the wind and could snap.
- When planting bulbs make a deep hole, about four times the diameter of the bulb.
- Small varieties should be planted about 10cm apart, while taller ones need to be at least 20cm apart.
- Water well after planting, saturating the soil around the bulbs.
If you have bought plants rather than bulbs, transfer them out to the garden in late spring/early summer. Ease them carefully out of the pot and transfer to a hole with a good handful of grit at the bottom to help drainage. Firm the soil around the plant and water well. Keep an eye on new plants during hot spells but they are generally drought tolerant once established.
Another one of our tips for how to plant allium bulbs is to grow alliums among herbaceous plants or ornamental grasses. Their strappy leaves often take on a yellow hue before they flower which can look a little unsightly, so this is less noticeable when mixed in with other foliage. It also helps to disguise the leaves when they die back after flowering.
Can I plant allium bulbs in a container?
Allium schubertii: large flower balls with exploding spikes make it look like a firework
As long as the pot is deep enough your alliums will do well as part of your container gardening ideas. Mix equal parts of peat-free multi-purpose compost and horticultural grit to get the free draining soil that alliums love.
One thing to remember when considering how to plant allium bulbs in pots is to factor in the final height of your alliums. This is important so that the container looks in proportion to your plants. As with all pot-grown plants they will need watering more than if they’re planted in the ground. Our guide on watering plants has some useful tips.
Are alliums self-seeding?
How to grow alliums: divide up clumps to increase your stock
Alliums are self-seeders, which is great if you favor a naturalistic look, for example if you're rewilding your garden. But if you want them to grow in a more controlled way, snip off any faded flower heads before they have the chance to scatter their seeds around.
Lift, divide and replant clumps of alliums every few years at the end of summer to regenerate your plants.
What allium bulbs should I choose?
Purple alliums are the best known variety
Most allium flowers are purple but they also come in shades of blue, white, pink and even yellow, so you'll be able to find a variety to suit your garden color schemes. Flower sizes range from just a few centimeters to over 15cm (6in) in diameter, while the height of alliums can also vary significantly.
Big varieties such as ‘Purple Rain’ and ‘Globemaster’ work well when planted individually or in drifts. Shorter varieties such as sparkly silver filigree Allium christophii work well in pots.
Try Allium schubertii for blooms that look like fireworks, Allium nigrum for a cool white bloom with grey foliage, Allium sphaerocephalon for unusual oval flowers and Allium siculum if you particularly want to attract bees.
If pink is your thing, opt for elegant ‘Summer Beauty’. Essentially lilac-tinged pink, it will add a touch of romantic planting to your garden borders.
